The aim of this study is to understand the ability of stewardship theory, as compared with agency theory, to explain motivation of staff in Not-for-Profit (NFP) organisations. Agency theory is seen as providing an explanation of motivation in the business sector however the different cultural and organisational conditions weaken the explanatory power of agency theory in the NFP sector. The interviews sought to answer question: what is the main source of motivation in the organisation? Analysis of interview data has shown that a stewardship theory framework best explains motivation of employees in the NFP sector.